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PVB location, inside or out?

I know most systems have the pvb(pressure/vacuum breaker) mounted outside. But, a friend mounted his inside up in the joists in his basement(the pvb would be high enough above grade to do so). Doing so would allow me to plumb two lines out each side of my house directly to the ideal box locations. The traditional way would be to go out the back to the pvb mounted outside and tee off in both directions around to the sides of the house adding a significant length in piping. Its also a much easier plumbing route to exit the house out the sides rather than the back. I checked the codes and its an acceptable way to do it. It seams the better way for me, but Im hesitant since all Ive ever seen have the pvb outside. Any comments, one way or the other?

Your local codes accepts a PVB installed indoors?? A PVB ( if this is what you do have) is ment to dump water right off the top if you have a problem. I guess if you wish to get water all over your house- then go for it but that is what will happen. These backflows must be installed and always be under constant pressure also or it defeats the purpose

If you want to do an indoors install you need a dual check valve or reduced pressure vacum breaker that is connected to a drain or sump area when it dumps water.

Thanks for the reply. Yes, the local code does allow a PVB to be installed indoors. The only requirement is that it be at least 12" about grade(or the highest down stream discharge device). Not sure what you mean when you say "A PVB ( if this is what you do have) is ment to dump water right off the top if you have a problem". I thought it was meant to be an anti-backflow device that is used to protect the potable water supply from backsiphonage. I'm also not sure what you meant when you say "these backflows must always be under constant pressure also or it defeats the purpose"??? Anyway, I appreciate your comments and will probably mount it outside since it is the proper way to do it.

A PVB (Pressure Vacume Breaker)purpose is when you do have back pressure situation, the device will automatically dump the reverse flow from your sprinkler system out of the top and onto the ground. The whole mechanics of it only work with your main under pressure.

Most counties atleast here in the east coast only allow PVB's on residential due to the fact that they flush out of the top and one is able to notice that it did and you know that it is working correctly.

I'm not sure if your getting into the business of irrigation- if you are you need to educate yourself on backflow prevention (Cross Connection)

If these devices are not installed and working properly- You can easily kill people with contaminated drinking water.

If you are using a well water source that is only for irrigation, no need for these devices.

If anyone wants a great resource on Backflow prevention, send me your email and I'll send you a pdf file

There is nothing wrong with installing a PVB indoors (from a safety stand point). It's just that if something does occur that attempts to "push" the water backwards, the PVB keeps you safe by spilling water out the top of it rather than letting it flow backwards into the plumbing that feeds potable water to the house (so you could end up with a wet basement, or where ever you install the PVB).

But for the PVB to operate correctly, the water line must be under constant pressure (therefore the PVB is installed upstream of any irrigation valves) and it can not be submerged (therefore the code specification that it be 12" above grade.

Thanks for clarifying things HooKooDooKu. After seeing a cross section of the internal workings of a PVB, I see there is no reason I can't install it indoors. I see that if you were to loose main water supply pressure to the PVB (extremely unlikely), AND you have a situation where backflow pressure was possible (such as downstream plumbing was above the PVB discharge), then water could backflow through the drain vent. But, in my situation where the PVB is mounted more than 12" above grade AND THE HIGHEST DOWNSTREAM DISCHARGE POINT, backflow is all but impossible (water doesn't flow up hill). Perhaps aquamatic should educate himself if he believes that (codes) "only allow PVB's on residential due to the fact that they flush out of the top and one is able to notice that it did and you know that it is working correctly". The only way a PVB could flush out of the top in my situation is if it were to mechanically fail. Thanks again HooKooDooKu

FixItDaddy- I am speaking for codes related to our area- If you would have read my entire quote on codes( most counties) 4 out of the 25 season startup we did last week had failed PVB's 1 of them was working fine when we started them up just to have the customer call us back two days later- It-s a mechanical device and failures can happen. The inside freeze protect bursted into pieces and the entire pressure flow was flowing off the top ( nothing to even do with the backpressure). The homeowner noticed by constantly hearing his water flow running - then noticed the pool of water outside by his PVB

Now lets imagine the same scenerio happens on a PVB that is stored indoors while the homeowner is away- Codes or no codes--- I think it makes more sense to mount it outdoors

If you want to install an indoor system go with an RPZ (If you know what they are) which the overflow is plumbed directly to a drain system.

As for educating myself- Maybe you should be a little careful on your words-
My opinion is not only backed with some education of national plumbing codes and knowledge of cross-connection prevention but experience and practical sense of what goes on and what could happen if a contarctor installs a device that could cause a homeowners basement to flood-

I noticed a few of your posts contradicts why certain things are done and why not your way because it makes sense to you- It actually sets apart a professional from an unprofessional- and its obvious where you fall.

We are setup in this forum to help each other out- not to insult our intelligence I have learned quite a bit myself from many others- My apologies to all others for such a defensive reply-

Aquamatic, Maybe if the PVB was properly drained (or mounted inside) it wouldn't have froze and "bursted".
As for the reduced pressure zone (yes I know what it is), it should be used if any sprinkler outlet is higher than the backflow preventer. It's usually a last resort to a PVB or AVB since it requires an annual inspection and a rebuild every 5 years.
As for education, I have a B.S. in Mechanical Engineering (your spelling and grammar speaks for itself).
Thank you for your comments on the subject and no further information will be required.

You should not have cast stones. You need to check your first three posts here and check your spelling.

I was a Manufacturing Engineer for 28 years and am now a Texas Licensed Irrigator, but I can still spell something wrong. What's the big deal about someone's education level. As far as I know, Aquamatic has a PhD in Nuclear Physics and just elects not to reveal it to us.

Also, I believe you and Aquamatic should have stated where you live before getting into a p**ssing contest. Here in Texas, besides State regulations, each municipality and even each subdivision can have it's own regulations that are tougher than the state and many of them do. Which is why I would not get into an argument with anyone around the Houston area that has worked in a different municipality or subdivision than I have personally done work in or have called and gotten the codes for.

As for Aquamatic, he has helped me tremendously on other forums and thru (manufacturing engineering spelling for through) private mail correspondence.